On the interface states and series resistance profiles of (Ni/Au)–Al0.22Ga0.78N/AlN/GaN heterostructures before and after 60Co (γ-ray) irradiation

Abstract

The values of interface states (N SS) and series resistance (R S) of (Ni/Au)–Al0.22Ga0.78N/AlN/GaN heterostructures were obtained from admittance and current–voltage measurements before and after 250 kGy 60Co irradiation. The analyses of these data indicate that the values of capacitance and conductance decrease, as the R S increases with increasing dose rate due to the generation of N SS. The increase in R S with increasing dose rate was attributed to two main models. According to the first model, it has been attributed to a direct decrease in the donor concentration in semiconductor material as a result of the elimination of shallow donor states. According to the second model, it is a result of irradiation because of the formation of deep acceptor centers in the semiconductor bulk, and electrons from the shallow donor centers are captured by these acceptors.